1. Field of Invention
The invention relates to an image forming apparatus that forms an image by exposing a photosensitive member to a plurality of laser beams.
2. Description of Related Art
A laser printer is generally known as an electrophotographic image forming apparatus. In the laser printer, a uniformly charged surface of a photosensitive member is exposed to a beam of laser light emitted based on image data, to form an electrostatic latent image on the surface of the photosensitive member. The electrostatic latent image attaches toner thereto. An image is formed onto a sheet as the tone is transferred to the sheet.
As disclosed in, for example, U.S. Pat. No. 6,476,846, a plurality of laser beam emitting devices that emit laser beams are provided for a laser printer. The resolution of an image is improved by exposing the photosensitive member to the laser beams emitted from each of the plurality of laser beam emitting devices.
More specifically, as two laser beam emitting devices are controlled in parallel, the photosensitive member is scanned with the laser beams two lines at a time. Thus, line density is increased without reducing the rotating speed of the photosensitive member.
For example, an image of 1200 dpi resolution is formed with a laser printer having two laser beam emitting devices, by driving the photosensitive member at the same rotating speed as an image of 600 dpi resolution is formed with one laser beam emitting device.
For example, Japanese Laid Open Patent Publication No. 10-202942 discloses an image forming apparatus capable of scanning two lines at a time, using two laser diodes. In the image forming apparatus, driving of one of the laser diodes is stopped to thin out or skip one line. Accordingly, a toner consumption amount can be reduced.